– THE LATEST ALL SOUTH AFRICAN PLANE!

(GUY LEITCH) – The iconic original J3 Piper Cub is now 84 years old. There have been countless attempts to build a modern version that does everything better. Has a small but passionate South African team got it right?

Guy Leitch.

THE LATEST VERSION of the venerable Piper Cub is the Orion Cub from Orion Aircraft in Krugersdorp.

Kevin Hopper owns SkyworX Aviation AMO at Krugersdorp and is a shareholder of Orion Aircraft. He has that great combination of a fertile mind and the skills to make his visions a reality. A childhood model aircraft builder, Kevin naturally moved up to full-scale planes and has set a high standard, as evidenced in his restoration of a number of EAA Grand Champions. Kevin gained his world-class skills as a patternmaker for General Motors in Port Elizabeth and then rebuilding aircraft at 43 Air School.

From his base in Krugersdorp, he has rebuilt almost 20 Tiger Moths, including Airlink CEO Rodger Foster’s prize-winning example, many J-3s and various other classic and more modern light aircraft.

Kevin has had a lifelong love affair with the basic Cub design. Fifteen years ago, he had his first serious attempt to build a better Cub by designing and building the Skyworx SW-18 Teddy. He stuck to affordable and readily available materials, so the Teddy was built out of wood and fabric. SA Flyer was the first to flight test this plane back in 2008 and it had indeed improved on the basic Cub. Sales were not however all that had been hoped for – perhaps due to the design being wood and fabric.

From his experience with the Teddy, Kevin knew he wanted to go bigger and stronger, and build an all-weather plane that could live outside. That required an all-aluminium wing and a steel tube fuselage. To help fund the project, he joined forces with two of his loyal clients and friends Eddie Scholtz and Roy Miller. To aid in the design and build process, Kevin brought on staff his son Dean Hopper and friend Aidan Cantin, who together refined and completed the Orion design.

Finally ready to fly after its long design and build process – the fit and finish are amazing for a prototype.

The first point of departure was that the plane needed to be more Super Cub than a basic J3. Thus, the design needed to have flaps, it had to be flown from the front seat, and should have a modern enclosed engine. Other key design requirements were: a large cockpit capable of accommodating two big and tall South Africans and their bags. The aircraft had to be able to accept engines from a 100 hp Rotax to a 200 hp IO-360 Lycoming yet it had to be light enough to preform well with just 100 hp. The goal design empty weight was just 380 kg – with a Max All Up Weight of 800 kg.

When asked why he chose the Orion name, Kevin tells how his father had designed and built MG sports car replicas called the Orion. Kevin and his Dad learned a huge amount about materials and what works from these cars, and so it was to his Dad’s memory that he called his latest creation the Orion Cub.

A big early question for an aircraft designer is what wing profile will work best. With guidance from renowned aeronautical engineer Francois Jordaan, the Harry Riblett 30-613.5 aerofoil was chosen. This improves on the original Cub’s USA-35B aerofoil as it retains its excellent slow speed handling and very docile stall, and yet provides a reasonable turn of speed.

After a long period of design, research and development, not helped by the Covid lockdown, the first flight of the Orion Cub took place at Krugersdorp on 3 September, flown by well-known instructor, test, competition and balloon pilot Dale de Klerk. Before the flight Dale showed us the key features of this latest and very impressive utility STOL plane.

Wing has all-metal construction and lots of ribs.

On The Ground

The first thing that strikes you is that it is indeed a significantly larger and more substantial plane than the basic J3 Cub. Standing tall on its shock absorbing undercarriage, shod with chunky 21/800 tyres, the Orion has loads of much sought-after ramp appeal. Noticeable at first glance are the large windows.

For a tandem design the Orion has a spacious 77cm (30 inch) wide cockpit, accessed by a single door and window on the right-hand side. The door is big enough to make access in and out of both front and back seats easy. Like a true Cub, the door is split horizontally; the top half is top-hinged so it can be swung up and latched against the bottom of the wing. Unlike the Cubs though, the lower section is hinged at the front, which means it can’t be folded down flat against the fuselage in flight. Being front hinged, the door allows pilot and passenger easy access to the cockpit, and with the rear seat hinged forward, bags are easily lowered into the ample space behind the rear seat. Production models will have baggage doors fitted as standard.

‘Big and tall South Africans and their bags’

The unusual slim-line seats have headrests and appear to be derived from automotive car racing seats. They are fully adjustable and the front seat can be flipped forward to make it even easier to get into the back seat.

For a utility bush plane the fit and finish are exemplary. The paint job has the lustre worthy of a supercar. The wing skins and ailerons are flush riveted with dimpled skins and countersunk Avex rivets. The wing skin is 6061 T6 aluminium and Kevin Hopper points out that the dimpled skins provide a far stronger shear strength than a smooth skin. The main and rear spars are custom extruded 6061 T6 I-beam sections. For the home builder the wings are all pre-drilled and key components are fabricated using a precision CNC router.

There are 45 litre fuel tanks in each wing, but Kevin says the standard tanks will be 50 or an optional 75 litres a side. In keeping with the need for simplicity, the fuel gauges are sight tubes in the wing roots. They are marked to read with the tail on the ground – but there is minimal change with the tail up while flying.

Any serious bush plane must have big tyres and the Orion has impressive enough 21-inchers. Much attention was given to the shock absorbing suspension. A composite spring bow was tried, but it induced a rolling gait on uneven surfaces so custom shock absorbers were made in a trapezoidal design. The resultant ladder frame may have more drag than a simple bowed leg, but the Cub is designed to operate off rough bush strips – rather than be a speedy cross-country machine.

At the rear the full swivelling steerable tailwheel is a substantial structure – also with its own built-in shock absorber. The fuselage is standard rag and tube; that is, a fabric covered tubular chromoly frame.

On the prototype ZU-IVS, the propeller is an inflight adjustable three blade Neuform prop, but constant speed units are available to improve takeoff performance.

For quick pre-flight access to the dipstick and coolant there is a separate hatch in the top cowl. Easy access to the whole engine is important for a bush plane, so both composite cowls can be removed with a simple fuel-tester screwdriver by undoing the 20 Camloc fasteners. Inside is the ubiquitous 100 hp Rotax 912ULS.

With the cowls off, the coolant radiator can be seen attached to the engine mount below the engine and the oil cooler is on the left side wall – with cool air supplied by a large NACA duct on the lower cowl.

The pre-flight is straightforward. Standing on the fat tyres gives access to the fuel tanks. Each fuel tank has two fuel feed points – one at the front and one at the back so the fuel feed pipe should never be uncovered in a dive or steep climb. The breathers for the fuel tanks are on the filler caps and each tank has its own drain near the wing root and beneath the rear seat there is a drain at the lowest point of the fuel system. The gascolator is in the engine compartment.

Flying the Orion

As the Orion was still in its testing phase, where passengers cannot be carried, we rely on test pilot Dale de Klerk’s report of the flying qualities.

Unlike the basic J3 Cub, the Orion is flown from the front. Climbing into the front seat is helped by the ladder frame undercarriage; right foot on the step, grip the crossbar in the roof, head forward into the cockpit, left foot to the left of the stick, slight your butt onto the seat, and you’re in. The front seat is spacious and there’s lots of head room. For the vertically challenged, the front seat is mounted on a rail secured with split pins to accommodate different positions of the seat, but it must be adjusted before you climb in. The rail is angled up, which raises the seat squab when it is moved forward.

‘excellent slow speed handling’

Getting into the rear seat is not too much of a challenge for unsupple old folk. Slide your butt in and then swing your legs up. Once seated in the back, you soon realise that this is no small aircraft.

The flap lever in located in the roof with a ratchet to select the positions. Standard settings are: 15, 30 and 45 degrees. A 60-degree position was considered but considered unnecessary – and risky in terms of the drag created should a go-around be required.

The cockpit layout is as basic as befits this type of aircraft and in particular, its prototype status. Both front and rear seats get a throttle lever on the left sidewall. Being a Rotax there is a choke lever and no mixture control or carb heat.

The fuel selector is located on the left cockpit sidewall, with Left, Right, Both as well as Off selections. The elevator trim is electric and located conveniently on the instrument panel – and not as the traditional Cub coffee grinder handle in the roof.

Flight instruments are on the left, engine instruments on the right of the panel. In the lower middle of the instrument panel there the Master and Avionics switches. The primary instruments are still the basic 2 ¼ inch ‘steam gauge’ dials. In the centre there is plenty of space for an EFIS ‘glass cockpit’ installation.

Starting the Rotax is standard. Leave the throttle cracked open and the 912 roars into busy geared life when the starter is cranked. The Orion has tuned length exhaust which keeps the noise level down – useful considering the minimal sound insulation.

‘shock absorbing suspension’

Taxiing the Orion is a breeze. There is good visibility over the nose and steering is direct from the steerable tailwheel. Taxiing across rough terrain is a pleasure as you hardly feel the ground beneath you – bumps are absorbed by those big tyres and two large shock absorbers. The elevator is mass balanced so the stick remains in the neutral position – and a firm forward pressure is needed to lift the tailwheel on takeoff.

The windows can be left open for takeoff and cruise. Thanks to the low window-line, the visibility out of the Orion is excellent.

Flying ZU-IVS

Even with just the 100 hp Rotax, acceleration is brisk and the stick almost instantly follows the throttle’s direction to raise the tail. The tail lifts quickly and direction is maintained with ease, thanks to the large rudder. The Orion is airborne at 50 mph within 100 metres. Climb out at 60 mph gives a high noise attitude and 950 fpm on the Highveld on a on a warm 26-degree Celsius September afternoon, with one up and 50 litres of fuel.

Levelling off at 6500 ft and 5,200 RPM indicates 95 mph, (105mph TAS) burning around 17 litres per hour – a comfortable cruise. With standard full tanks of 100 litres an endurance of five hours is possible with legal reserves.

Control harmony is well balanced on the Orion, making it a pleasure to fly. The elevator is driven by pushrods while the rudder and ailerons are connected by cables over pulleys and have a small null zone and break-out force. Adverse aileron yaw is minimal and turns can be achieved without the use of rudder This makes the Orion a delight to fly.

As intended by the Harry Riblett aerofoil, the stall is indeed benign – and remarkably slow. With flaps up, throttling back and raising the nose, the Orion will gently start mushing at around 30 mph indicated, with the ailerons fully effective throughout the (non) stall. With flaps down, the airspeed indicator reads an incredible 25 mph. Dale de Klerk does however concede that there may be position error on the protype. Amazingly though, the Computer Assisted Design program also predicted a 25 mph stall with flap – and it has proven accurate to within 5%. To unstall the wing simply release back pressure and it starts flying again.

The Orion Cub has much sought-after strong ramp presence.

With the power at idle and flaps up, a descent of 400 fpm is achieved at 50 mph. Final approach is flown at50 mph, with45 mph across the fence. Sideslips can be used to lose height and speed even faster, but should hardly be needed if the circuit is flown at the correct speeds.

Smooth 3-point and wheeler landings are easy to achieve and even a bad landing is absorbed by the cushioning wheels and shock absorbers. Dale is confident that the Orion will comfortably manage takeoffs and landing within 50 metres.

Thanks to the good view forward you don’t lose visibility to the front in a 3-point landing, so it’s a matter of personal preference which technique is used. 3-point landings are preferred for short field operations; the Orion’s natural territory.

‘Fit and finish are exemplary’

Wrap-Up

Despite being a prototype, the Orion is a remarkably refined design and thus a good all-rounder with great short field and slow performance. Plus, there is a more than respectable 100 mph cruise speed, and it will carry two average South Africans and go just about anywhere. In contrast with the Bearhawk LSA, the Orion may be slightly slower, but it has better slow speed handling, significantly lower stall speeds and thus much reduced runway requirements. I reckon it would be an easy thing for the Orion creators to offer a short-wing version for those who do not require the full STOL bush plane capability.

‘a super STOL contender’

Kevin Hopper says that being a South African design and build is a real advantage in avoiding the need to undergo the CAA’s expensive overseas inspection process. Although instruments, engine and brakes are all sourced outside of the country, almost everything else can be obtained locally, protecting them from currency instability and ensuring a reliable delivery period for customers.

For the pleasure of owning or building a brand-new plane, the prices are excellent. The basic kit is just U$ 34,000. With everything assembled, but excluding the engine, prop and avionics, the kit price is U$52,500. Ready to fly depends on final specification, but budget on U$100,000.

With a design take-off weight of 800kg the beauty of the Orion is that it is designed to fly outside the LSA category and it can carry a large useful load a long way. Alternatively, with the 100 hp Rotax, the Orion can be registered with a max all up weight of 600kg as an LSA. It should weigh in at 380 kg empty, allowing for 220 kg of useful load. Registering it outside the LSA category allows 420 kg of useful load – which is more than the weight of the empty aircraft!

Engine options define the two types of Orion – the RS series is for lightweight engines – up to 110 kg, such as the Rotax 912 and UL Power engines and it has a slightly shorter rear fuselage to match the light weight. The LC series is for Lycoming or Continental type engines and comes with a longer fuselage to compensate for the heavier engines and props. The bigger engines can be as powerful as 200 hp, which will make the Orion a super STOL contender.

With the current strong swing to bush planes and STOL flying, Kevin Hopper and his team have hit the sweet spot with the Orion. They are sure to have a winner and demand for construction positions has been gratifyingly strong.

Specifications and Performance

ZU-IVS Prototype  
Specifications
Wingspan:32.4ft
Fuel capacity:90 litres
Gross weight (ORION):800 kg (or 600 for LSA)
Empty weight380 kg
Full fuel payload346 kg (146 kg as LSA)
Seating capacity:2 Tandem
Baggage Capacity:30 kg
        Performance
Powerplant:Rotax 912 ULS
Horsepower:100
Propeller:Neuform 3 blade
Cruise speed:95 mph
Rate of climb:850 fpm (on the Reef)
Stall speed (w flap):25 mph
Take off distance:100 m
Landing distance:100 m

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